Inflammation is a key aspect of wound healing. In treatment of periodontal disease, periodontal regeneration of inflammation-mediated damage requires stem cell activity in the formation of bone periodontal ligament and cementum. The hypothesis considered in this project is that "inflammatory signaling through NF-KB modulates stem cell differentiation along the osteoblastic lineage". Only limited information is available regarding this aspect of mesenchymal stem cell biology, and there is the confounding possibility that inflammatory signals can be both positive and negative effectors of stem cell engraftment, specification and differentiation. Our long range goal of defining mesenchymal stem cell responses to NF-KB-mediated inflammatory stimuli may indicate new targets for improving periodontal regeneration. Experiments are proposed to address the following specific aims: I) to define the effect of NF-KB on mesenchymal stem cell osteoblastic differentiation;IicB super-repressor will be used to modulate cell function and pharmacologic inhibitors of IKK will be used to determine NF-KB effects on hMSCs. II) to determine the role of NF-KB on osteoinductive signaling;transient transfection of stem-like and osteoblastic cell lines will be used to define how inflammatory stimuli affect a) Smad signaling, b) RUNX2 transactivation and c) LRP5 signal transduction. Ill) to target inflammation in the therapeutic modulation of stem cell function during bone regeneration;a p6s cre/lox conditional knockout mouse will be used as a source of NF-KB deficient cells to study its role during stem cell engraftment and differentiation observed in ectopic bone formation models. Osteoblastic cell lines and human MSCs expressing NF-KB or IKB super-repressor will also be used to study inflammation effects on osteoinduction. Challenging these models with inflammatory agens and blocking with IKK inhibitors is proposed. Characterization of inflammatory signaling effects of the emergence bone forming cells for tissue repair may identify new therapeutic targets and avenues for treatment of chronic inflammatory diseases like periodontitis.